When an effect is suppressed, it means it no longer has any effect. This can happen in various ways (like an anti-magic field). The duration of the suppressed effect is usually not changed and if, when the suppressor ends, the effect is still present then its effects return.
So, a character has the shaken condition. A cleric uses Freedom's Call. As long as the Call is active (and the character in the radius), the character does not take any of the penalties described in that condition's entry
Likewise, 'Grappled' is a condition:
A grappled creature is restrained by a creature, trap, or effect. Grappled creatures cannot move and take a –4 penalty to Dexterity. A grappled creature takes a –2 penalty on all attack rolls and combat maneuver checks, except those made to grapple or escape a grapple. In addition, grappled creatures can take no action that requires two hands to perform. A grappled character who attempts to cast a spell or use a spell-like ability must make a concentration check (DC 10 + grappler's CMB + spell level), or lose the spell. Grappled creatures cannot make attacks of opportunity.
A grappled creature cannot use Stealth to hide from the creature grappling it, even if a special ability, such as hide in plain sight, would normally allow it to do so. If a grappled creature becomes invisible, through a spell or other ability, it gains a +2 circumstance bonus on its CMD to avoid being grappled, but receives no other benefit.
Casting Spells while Grappled/Grappling: The only spells which can be cast while grappling or pinned are those without somatic components and whose material components (if any) you have in hand. Even so, you must make a concentration check (DC 10 + the grappler's CMB + the level of the spell you're casting) or lose the spell.
While under the effect of the Call, a character would be able to move and act normally. While it is not stated, I would rule that if a grappled character moved away from its grappler, it would no longer be grappled. Likewise, if a character did NOT move before the Call ended, it would still be grappled just as is was before.
This would all be automatic with no rolls being made (beyond attacks of opportunity and actions and whatnot).